syzbot

INFO: task loop0:3957 blocked for more than 120 seconds.
      Not tainted 4.4.138-g226f96b #63
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
loop0           D ffff8801d6d5ed40 26880  3957      2 0x00000000
 ffff8801d6d5ed40 0000000000000003 ffff8800bbb94800 ffffffff838c3329
 ffff8801d6d5ee00 ffff8801db31fdb8 ffff8801db31fde0 ffff8801db31f4d8
 ffff8801db31f4c0 ffff8801d7ca9800 ffff8800bbb94800 ffff8801d6d5f610
Call Trace:
 [<ffffffff838b46ea>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff838bfb01>] schedule_timeout+0x481/0x8b0 kernel/time/timer.c:1515
 [<ffffffff838b25aa>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:4941
 [<ffffffff81db234f>] io_schedule include/linux/sched.h:447 [inline]
 [<ffffffff81db234f>] bt_get+0x2af/0x760 block/blk-mq-tag.c:301
 [<ffffffff81db3645>] __blk_mq_get_tag block/blk-mq-tag.c:325 [inline]
 [<ffffffff81db3645>] blk_mq_get_tag+0x1f5/0x360 block/blk-mq-tag.c:353
 [<ffffffff81da3307>] __blk_mq_alloc_request+0x27/0xa40 block/blk-mq.c:215
 [<ffffffff81da94b2>] blk_mq_map_request.isra.42+0x732/0xe00 block/blk-mq.c:1190
 [<ffffffff81dad52d>] blk_sq_make_request+0x1ad/0xe60 block/blk-mq.c:1361
 [<ffffffff81d7f541>] generic_make_request+0x211/0x9b0 block/blk-core.c:2081
 [<ffffffff81d7fdbf>] submit_bio+0xdf/0x3b0 block/blk-core.c:2154
 [<ffffffff815e1aab>] dio_bio_submit fs/direct-io.c:409 [inline]
 [<ffffffff815e1aab>] do_blockdev_direct_IO+0x5aab/0x82f0 fs/direct-io.c:1283
 [<ffffffff815e439e>] __blockdev_direct_IO+0xae/0xe0 fs/direct-io.c:1342
 [<ffffffff815d1182>] blkdev_direct_IO+0xb2/0xe0 fs/block_dev.c:167
 [<ffffffff8142417c>] generic_file_read_iter+0x35c/0x11a0 mm/filemap.c:1799
 [<ffffffff815d3e85>] blkdev_read_iter+0x105/0x170 fs/block_dev.c:1679
 [<ffffffff8251e221>] lo_rw_aio+0x481/0x870 drivers/block/loop.c:506
 [<ffffffff82520477>] lo_rw_simple drivers/block/loop.c:520 [inline]
 [<ffffffff82520477>] do_req_filebacked drivers/block/loop.c:558 [inline]
 [<ffffffff82520477>] loop_handle_cmd drivers/block/loop.c:1705 [inline]
 [<ffffffff82520477>] loop_queue_work+0x12b7/0x1620 drivers/block/loop.c:1717
 [<ffffffff81190c73>] kthread_worker_fn+0x1c3/0x610 kernel/kthread.c:602
 [<ffffffff81190958>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff838c2b55>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
no locks held by loop0/3957.
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 3956 Comm: syz-executor795 Not tainted 4.4.138-g226f96b #63
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bbb91800 task.stack: ffff8800b9ac0000
RIP: 0010:[<ffffffff813514b1>]  [<ffffffff813514b1>] __sanitizer_cov_trace_pc+0x1/0x50 kernel/kcov.c:93
RSP: 0018:ffff8800b9ac7610  EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000200000
RDX: 0000000000000004 RSI: 1ffff10017358ec9 RDI: 0000000000000001
RBP: ffff8800b9ac76f0 R08: 0000000000000000 R09: ffff8800b9ac7748
R10: 0000000000000000 R11: ffff8800bbb91800 R12: ffff8800b9ac7748
R13: 0000000000200000 R14: 0000000000000001 R15: 0000000000000001
FS:  00000000006e2880(0063) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555c4b6ae000 CR3: 00000000bab33000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8800b9ac76f0 ffffffff81c55d5a ffff8800bbb92150 ffff8800bbb920e0
 1ffff10000000000 1ffff10017358ec9 0004000000200000 0000000041b58ab3
 ffffffff842041ad ffffffff81c55cc0 ffff8800bbb920f8 ffffffff85389fa0
Call Trace:
 [<ffffffff81c659f6>] cred_has_capability+0x126/0x2a0 security/selinux/hooks.c:1576
 [<ffffffff81c65bb9>] selinux_vm_enough_memory+0x49/0x60 security/selinux/hooks.c:2146
 [<ffffffff81c4af97>] security_vm_enough_memory_mm+0x77/0xb0 security/security.c:230
 [<ffffffff81465099>] shmem_acct_block mm/shmem.c:179 [inline]
 [<ffffffff81465099>] shmem_getpage_gfp+0x9a9/0x1250 mm/shmem.c:1178
 [<ffffffff81465a27>] shmem_getpage mm/shmem.c:130 [inline]
 [<ffffffff81465a27>] shmem_write_begin+0xe7/0x190 mm/shmem.c:1507
 [<ffffffff8141de3f>] generic_perform_write+0x32f/0x540 mm/filemap.c:2578
 [<ffffffff81423292>] __generic_file_write_iter+0x362/0x550 mm/filemap.c:2703
 [<ffffffff8142376d>] generic_file_write_iter+0x2ed/0x710 mm/filemap.c:2731
 [<ffffffff8151d8fc>] do_iter_readv_writev+0x13c/0x1e0 fs/read_write.c:664
 [<ffffffff8151f020>] do_readv_writev+0x2e0/0x6e0 fs/read_write.c:808
 [<ffffffff8151f54b>] vfs_writev+0x7b/0xb0 fs/read_write.c:847
 [<ffffffff81521f4a>] SYSC_pwritev fs/read_write.c:936 [inline]
 [<ffffffff81521f4a>] SyS_pwritev+0x18a/0x230 fs/read_write.c:922
 [<ffffffff838c2725>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: ff e8 24 84 1a 00 eb 85 4c 89 e7 e8 7a 83 1a 00 eb b7 e8 13 84 1a 00 eb 89 4c 89 e7 e8 69 83 1a 00 e9 14 ff ff ff 0f 1f 40 00 55 <48> 89 e5 65 48 8b 04 25 00 67 01 00 65 8b 15 cc 51 cc 7e 81 e2 
NMI backtrace for cpu 1
CPU: 1 PID: 491 Comm: khungtaskd Not tainted 4.4.138-g226f96b #63
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d8dde000 task.stack: ffff8801d8df8000
RIP: 0010:[<ffffffff810bfb26>]  [<ffffffff810bfb26>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810bfb26>]  [<ffffffff810bfb26>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810bfb26>]  [<ffffffff810bfb26>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810bfb26>]  [<ffffffff810bfb26>] flat_send_IPI_mask+0xf6/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8801d8dffcc8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8801d8dffcf0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: 0000000000000002 R15: ffffffff8446f6a0
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc8febb28b CR3: 00000000b35cf000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8446f6a0 ffffffff84a18ee0 0000000000000007 fffffbfff0942c8c
 0000000000000040 ffff8801d8dffd10 ffffffff810b5ae1 ffffffff83c0b460
 0000000000000003 ffff8801d8dffd68 ffffffff81e19d83 ffff8800bbb94800
Call Trace:
 [<ffffffff810b5ae1>] nmi_raise_cpu_backtrace+0x61/0x80 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81e19d83>] nmi_trigger_all_cpu_backtrace.cold.4+0x70/0xad lib/nmi_backtrace.c:85
 [<ffffffff810b5b84>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff8141a459>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff8141a459>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8141a459>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8141a459>] watchdog.cold.1+0xd3/0xee kernel/hung_task.c:238
 [<ffffffff81190958>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff838c2b55>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
Code: b3 5f ff f6 c4 10 75 e2 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 f2 09 da 80 cf 04 41 83 fe 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 75 1a 4c 89 e7 57 9d 0f 1f 44 00 00 e8 02